I'm running XP also (LabVIEW 6.1) and I did not have any problems running these VIs. I've tried looking in what might cause that error (incompatible variant type) but can not find much associated with this VI. If you build your own VI, do you get the same error? I would assume you do if the examples are behaving this way. Do any of the Database examples run on your XP machines? I'm guessing it's either a problem with your database settings on the computers or some XP configuration.
J.R. Allen